The production and use of disposable containers, such as cups, is well known with production measured in the billions of units annually. Because of this volume, the business is fiercely competitive and cost is measured in units of one thousand. A change of a few percent in cost can make a container unsaleable, particularly to large fast food chains.
Paper and paperboard are widely used as materials in the production of disposable containers because they are inexpensive and amenable to very high volume production. They have limitations, however, particularly in containing hot liquids, such as coffee, tea, hot chocolate, etc., which are dispensed from vending machines or supplied in fast food or takeout restaurants. The initial temperature of coffee poured into a disposable cup can exceed 200 degrees Fahrenheit, resulting in the temperature on the outside of the disposable which is painful to hold. A typical reaction to this thermal pain can cause spillage, resulting in severe damage to the skin, and inevitable product liability litigation.
Thick walled insulated cups are bulky, taking up extensive volume in storage and disposal. The use of a thick walled insulated cup for cool beverages is not cost effective.
Accordingly, there still exists a need for an inexpensive container sleeve which provides a controlled amount of heat transfer to warn the user that a hot liquid is contained therein, which insulates sufficiently to protect against pain or burn, which is stackable for shipping and mass sales, and which is microwave compatible.